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Cyanobacterial Toxins, Drinking Water and Human Health
Wickramasinghe Wasantha A.,Shaw Glen R. Korean Society of Environmental Health 2005 한국환경보건학회지 Vol.31 No.3
The occurrence of toxic cyanobacterial blooms has been reported worldwide and poses a threat to human health through drinking water exposure. The toxins they produce are highly water soluble and can leach into the water body. To eliminate any risk of drinking water exposure, removal of these toxins is essential before the water is consumed. Conventional water treatment techniques such as chlorination, if managed well, can be effectively used to remove some of these toxins, however, saxitoxin and its derivatives pose a problem. Little toxicological data are available to evaluate the real threat of these toxins.
K. C Wickramasinghe,G. I. P. Perera,S. W. M. A. I Senevirathne,Himan KG Punchihewa,Hiroyuki Sasahara 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.12
Metal working fluid (MWF) plays a significant role in metal machining operations to obtain the desired dimensional accuracy and better surface quality in the machined component. Legislations have set limits on the usage of mineral based MWFs because of their carcinogenic behavior and adverse effect on health and the environment. The saturated fatty acid of vegetable oil facilitates a better layer of lubricant between work tool interface compared with the mineral oil based MWFs. This paper describes the surface quality of 0.2 % C and AISI 304 steels while using formulated novel white coconut oil based MWF and mineral oil based MWF in flood cooling and dry machining. The machining parameters were selected according to the recommended specifications, and quality of the machined surface was measured. The novel white coconut oil based MWF has expressed better surface quality for almost all the set of machining parameters compared to other cooling configurations.
Thermal Performance of Modular Multilevel Converters in HVDC Applications under Offset PWM
Harith R. Wickramasinghe,Weiyao Wang,Ke Ma,Georgios Konstantinou 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The total number of submodules (SMs) in a modular multilevel converter (MMC) can be utilized by considering an offset in the arm currents in order always operate at the maximum duty cycle. This article presents the thermal performance of an MMC for an HVDC application when considering its operation under offset PWM. It is demonstrated that the reduction of the total energy in the SM capacitors and the improved performance under faults with lower overall losses but with a variation in the distribution of losses among the devices within an SM. Simulation results based on detailed thermal models as well as experimental cases with thermal behavior demonstrate the impact of offset PWM in an MMC for HVDC applications.
Cyanobacterial Toxins and Drinking Water Guidelines
Wasantha A. Wickramasinghe,Glen R. Shaw 한국환경보건학회 2005 한국환경보건학회지 Vol.31 No.3
The occurrence of toxic cyanobacterial blooms has been reported worldwide and poses a threat to human health through drinking water exposure. The toxins they produce are highly water soluble and can leach into the water body. To eliminate any risk of drinking water exposure, removal of these toxins is essential before the water is consumed. Conventional water treatment techniques such as chlorination, if managed well, can be effectively used to remove some of these toxins, however, saxitoxin and its derivatives pose a problem. Little toxicological data are available to evaluate the real threat of these toxins
Are the Distribution of Einstein Crossing Times of Galactic Microlensing Events Bimodal?
Struble, Mitchell F.,Wickramasinghe, Thulsi 한국우주과학회 2012 Journal of Astronomy and Space Sciences Vol.29 No.2
The observed distribution of a blending-corrected sample of Einstein ring crossing times, tE, for microlensing events toward the galactic bulge/bar are analyzed. An inspection of the distribution of crossing times suggests that it may be bimodal, indicating that two populations of lenses could be responsible for observed microlensing events. Given the possibility that microlensing in this direction can be due to the two most common classes of stars, main-sequence and white dwarf, we analyze and show via Monte Carlo simulations that the observed bimodality of tE can be derived from their accepted mass functions, and the density distributions of both stellar populations in the galactic disk and bulge/bar, with a transverse velocity distribution that is consistent with the density distribution. Kolmogorov-Smirnov (KS) one sample tests shows that a white dwarf population of about 25% of all stars in the galaxy agrees well with the observed bimodality with a KS significance level greater than 97%. This is an expanded and updated version of a previous investigation (Wickramasinghe, Neusima, & Struble, in Mao 2008). A power-point version of the talk, with introductory figures, is found at: https://sites.google.com/site/rhkochconference/agenda-1/program.